Passage 3.11.1
ἀπὸ δὲ Θόρνακος προελθόντι ἔστιν ἡ πόλις, Σπάρτη μὲν ὀνομασθεῖσα ἐξ ἀρχῆς, προσλαβοῦσα δὲ ἀνὰ χρόνον καὶ Λακεδαίμων ἡ αὐτὴ καλεῖσθαι· τέως δὲ τὸ ὄνομα τοῦτο ἔκειτο τῇ γῇ. ὃ δὲ ἐν τῇ συγγραφῇ μοι τῇ Ἀτθίδι ἐπανόρθωμα ἐγένετο, μὴ τὰ πάντα με ἐφεξῆς, τὰ δὲ μάλιστα ἄξια μνήμης ἐπιλεξάμενον ἀπʼ αὐτῶν εἰρηκέναι, δηλώσω δὴ πρὸ τοῦ λόγου τοῦ ἐς Σπαρτιάτας· ἐμοὶ γὰρ ἐξ ἀρχῆς ἠθέλησεν ὁ λόγος ἀπὸ πολλῶν καὶ οὐκ ἀξίων ἀφηγήσεως, ὧν ἃ ἕκαστοι παρὰ σφίσι λέγουσιν, ἀποκρῖναι τὰ ἀξιολογώτατα. ὡς οὖν εὖ βεβουλευμένος οὐκ ἔστιν ὅπου παραβήσομαι.
After Thornax, as one proceeds further, comes the city originally called Sparta, which in time acquired the name Lacedaemon as well. Previously, this name belonged to the territory itself. Before embarking upon my account of the Spartans, I will explain here what served as a corrective measure in my Attic narrative—that I have chosen not to relate absolutely everything in order, but rather have carefully selected and recounted only those things most worthy of remembrance. Indeed, from the start, my purpose has been to gather from many sources—including those unworthy of detailed narration—the most noteworthy traditions that each people relates. Thus assured that my intention is rightly considered, there is no point at which I will deviate from it.